A battery pack may include a plurality of voltaic cell modules connected in series for increased voltage or in parallel for increased current handling. During charging or discharging, the modules may evolve excess heat, which may be released to the ambient to avoid an over-temperature condition. At very low ambient temperatures, the modules of the battery pack may be supplied heat in order to achieve or maintain a suitable operating temperature.
The modules of a battery back may be coupled to a substrate that can absorb heat—e.g., a substrate that conducts flowing water. Efficient heat transfer between the modules and the substrate may require at least a partial filling of air gaps—gaps between the modules, gaps between the modules and the substrate, etc.—with a thermally conductive material. However, silicone greases and the like, which have been used as a gap filler, may be difficult to apply in a consistent manner and may not provide adequate dielectric isolation.